method

has_many_attached

v7.2.3 - Show latest stable - Class: ActiveStorage::Attached::Model

has_many_attached(name, dependent: :purge_later, service: nil, strict_loading: false)

public

Specifies the relation between multiple attachments and the model.

class Gallery < ApplicationRecord
  has_many_attached :photos
end

There are no columns defined on the model side, Active Storage takes care of the mapping between your records and the attachments.

To avoid N+1 queries, you can include the attached blobs in your query like so:

Gallery.where(user: Current.user).with_attached_photos

Under the covers, this relationship is implemented as a has_many association to a ActiveStorage::Attachment record and a has_many-through association to a ActiveStorage::Blob record. These associations are available as photos_attachments and photos_blobs. But you shouldn’t need to work with these associations directly in most circumstances.

The system has been designed to having you go through the ActiveStorage::Attached::Many proxy that provides the dynamic proxy to the associations and factory methods, like #attach.

The :dependent option defaults to :purge_later. This means the attachments will be purged (i.e. destroyed) in the background whenever the record is destroyed. If an ActiveJob::Backend queue adapter is not set in the application set it to purge instead.

If you need the attachment to use a service which differs from the globally configured one, pass the :service option. For example:

class Gallery < ActiveRecord::Base
  has_many_attached :photos, service: :s3
end

:service can also be specified as a proc, and it will be called with the model instance:

class Gallery < ActiveRecord::Base
  has_many_attached :photos, service: ->(gallery) { gallery.personal? ? :personal_s3 : :s3 }
end

If you need to enable strict_loading to prevent lazy loading of attachments, pass the :strict_loading option. You can do:

class Gallery < ApplicationRecord
  has_many_attached :photos, strict_loading: true
end

Note: Active Storage relies on polymorphic associations, which in turn store class names in the database. When renaming classes that use has_many, make sure to also update the class names in the active_storage_attachments.record_type polymorphic type column of the corresponding rows.

# File activestorage/lib/active_storage/attached/model.rb, line 206
      def has_many_attached(name, dependent: :purge_later, service: nil, strict_loading: false)
        Attached::Model.validate_service_configuration(service, self, name) unless service.is_a?(Proc)

        generated_association_methods.class_eval           # frozen_string_literal: true          def #{name}            @active_storage_attached ||= {}            @active_storage_attached[:#{name}] ||= ActiveStorage::Attached::Many.new("#{name}", self)          end          def #{name}=(attachables)            attachables = Array(attachables).compact_blank            pending_uploads = attachment_changes["#{name}"].try(:pending_uploads)            attachment_changes["#{name}"] = if attachables.none?              ActiveStorage::Attached::Changes::DeleteMany.new("#{name}", self)            else              ActiveStorage::Attached::Changes::CreateMany.new("#{name}", self, attachables, pending_uploads: pending_uploads)            end          end, __FILE__, __LINE__ + 1

        has_many :"#{name}_attachments", -> { where(name: name) }, as: :record, class_name: "ActiveStorage::Attachment", inverse_of: :record, dependent: :destroy, strict_loading: strict_loading
        has_many :"#{name}_blobs", through: :"#{name}_attachments", class_name: "ActiveStorage::Blob", source: :blob, strict_loading: strict_loading

        scope :"with_attached_#{name}", -> {
          if ActiveStorage.track_variants
            includes("#{name}_attachments": { blob: {
              variant_records: { image_attachment: :blob },
              preview_image_attachment: { blob: { variant_records: { image_attachment: :blob } } }
            } })
          else
            includes("#{name}_attachments": :blob)
          end
        }

        after_save { attachment_changes[name.to_s]&.save }

        after_commit(on: %[ create update ]) { attachment_changes.delete(name.to_s).try(:upload) }

        reflection = ActiveRecord::Reflection.create(
          :has_many_attached,
          name,
          nil,
          { dependent: dependent, service_name: service },
          self
        )
        yield reflection if block_given?
        ActiveRecord::Reflection.add_attachment_reflection(self, name, reflection)
      end

has_many_attached

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